What can be done if the non-custodial parent is threatening to violate the custodial parent's custody rights?

The child is ordered summer visitation with the NCP (non-custodial parent). Because of a step-child (that has been in trouble with the Juvenile Courts) in the CP's home, the NCP does not want the child back in the CP's home. What would be the CP (custodial parent's options?

You would need to file a Petition for Modification of Custody, and request that the Court change the current visitation schedule so as to limit the Non-Custodial Parent's visitation time with the child. You will need to show the Court several compelling reasons for restricting his access to the child, and that such a restriction is in the child's best interests. It sounds like you have a few facts above, that would help your argument. You need to consult a local Atlanta attorney to discuss this matter further, and provide more facts. Many offer free consultations.